My Toyo 45A serves me well but if you might be looking for adventure I can recommend the Ilford Titan pinhole (4x5). Very light weight and great fun to use and is compatible with one of my lighter tripods. I've done pt/pd prints, silver gelatin and scans from the negatives. I just received the 150mm cone/pinhole and can't wait to try it. I know it doesn't replace a lens and movements or for that matter my Blads but it is a nice departure from lenses and focusing and with a light meter and several film holders fits in a fairly small backpack.

http://www.jeffreyglasser.com/